L cell and WEHI-3 cell lines will be used for the large scale production of several types of colony stimulating factors. L cell CSF will be purified by a rapid affinity chromatography technique whereas multiple chromotographic and density gradient steps will be utilized for purification of the granulocytic stimulator in WEHI-3 conditioned medium. Antibodies will be prepared against both factors and used to devise radioimmunoassays. The antibodies will be purified by affinity chromatographic techniques. These will be coupled to immunoadsorbents and the resultant gels will be used to concentrate CSF responsive cells. Binding of 125I CSF to marrow cells will be characterized using both macrophages (M) and granulocytic (G) varieties of CSF. Selective use of the purified regulator and cell populations will be utilized to determine whether the progenitor cells are unipotential or have the capability of differentiating into both granulocytes and macrophages. Prostaglandins and isoferritins, putative regulators of cell production, will be tested for possible interactions with CSF receptors. Both GCSF and MCSF will be injected into mice to determine whether serum activity controls the rate of cell production in vivo. Studies will be conducted with diffusion chambers in normal mice and in those with tumor induced granulocytosis to determine whether increased local CSF production may be the primary determinant of granulopoiesis and monocytopoiesis in vivo. Several human cell lines will be established for the large scale production of human-type colony stimulating factor in serum-free medium. These may ultimately be used for the purification of human-active CSF's.